US7335871B2 - Low power switching for antenna reconfiguration - Google Patents

Low power switching for antenna reconfiguration Download PDF

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Publication number
US7335871B2
US7335871B2 US11/253,188 US25318805A US7335871B2 US 7335871 B2 US7335871 B2 US 7335871B2 US 25318805 A US25318805 A US 25318805A US 7335871 B2 US7335871 B2 US 7335871B2
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Prior art keywords
light signal
light
duration
duty cycle
source
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US11/253,188
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US20070084987A1 (en
Inventor
Paul E. Bauhahn
Robert C. Becker
David W. Meyers
Kelly P. Muldoon
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Honeywell International Inc
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Honeywell International Inc
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Assigned to HONEYWELL INTERNATIONAL INC. reassignment HONEYWELL INTERNATIONAL INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BAUHAHN, PAUL E., BECKER, ROBERT C., MEYERS, DAVID W., MULDOON, KELLY P.
Assigned to NASA reassignment NASA CONFIRMATORY LICENSE (SEE DOCUMENT FOR DETAILS). Assignors: HONEYWELL INTERNATIONAL INC.
Priority to EP06117513A priority patent/EP1777820A3/de
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/78—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
    • H03K17/785—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled controlling field-effect transistor switches
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
    • H03K2217/0036—Means reducing energy consumption

Definitions

  • the present invention generally relates to radio frequency antennas and more particularly to switching reconfigurable antennas.
  • each optically coupled switch must be held in its present state.
  • the problem with current optically coupled switch systems and methods is that to hold a switch in its present state, a number of optical light sources must remain on for the duration of the steady-state antenna configuration.
  • a full antenna element array may include 800 optically controlled switches. Each switch might be controlled by a typical VCSEL light source that draws up to 45 mW to maintain a single optical switch in an off-state.
  • Embodiments of the present invention provide methods and systems for Low Power Switching for Antenna Reconfiguration and will be understood by reading and studying the following specification.
  • a method for antenna reconfiguration switching comprises directing a light signal at an optically controlled switch, wherein the optically controlled switch is adapted to open and close a current path between two pad elements of a reconfigurable antenna based on the light signal; and cycling the light signal on and off, wherein the light signal is cycled on for a sufficient duration of time and with a sufficient periodicity to maintain the optically controlled switch in one of an open state and a closed state.
  • a reconfigurable antenna system comprises a plurality of pad elements arranged in an array, wherein at least one pad element of the plurality of pad elements is adapted to be driven by an electrical signal; a plurality of switches, wherein each switch of the plurality of switches is adapted to switch together two or more pad elements of the plurality of pad elements; and a plurality of light sources, wherein each switch is maintained in one of an open state and a closed state based on a light signal output from an associated light source, wherein the light source cycles the light signal output on and off based on a duty cycle.
  • an optical switching system comprising at least one optically controlled switch adapted to maintain one of an open state and a closed state based on an associated light signal; and at least one light source adapted to output the associated light signal to the at least one switch, wherein the at least one light source cycles the light signal on and off, wherein the at least one light source is cycled on for a sufficient duration of time and with a sufficient periodicity to maintain the optically controlled switch in one of an open state and a closed state.
  • a system for switching comprises means for controlling current flow based on a switching voltage; means for generating a light signal, wherein the means for generating the light signal is adapted to cycle the light signal on and off; means for receiving a light signal responsive to the means for generating a light signal, wherein the means for receiving a light signal is coupled to the means for controlling current flow, wherein the means for receiving a light signal is adapted to produce the switching voltage when the light signal is received; and means for maintaining the switching voltage above a minimum voltage when the light signal is cycled off, wherein the means for maintaining the switching voltage is responsive to the means for receiving a light signal; wherein the light signal is cycled on for a sufficient duration of time and with a sufficient periodicity to maintain the means for a controlling current flow in one of an open state and a closed state.
  • FIGS. 1A and 1B are diagrams illustrating a reconfigurable antenna aperture of one embodiment of the present invention.
  • FIG. 2 is a diagram of an optical switch of one embodiment of the present invention.
  • FIG. 3 is a diagram illustrating the relationship between a duty cycled light signal and a switching voltage of one embodiment of the present invention
  • FIG. 4 is a diagram illustrating a reconfigurable antenna aperture of one embodiment of the present invention.
  • FIG. 5 is a flow chart illustrating a method of one embodiment of the present invention.
  • Embodiments of the present invention greatly reduce the power required to hold antenna configurations by duty-cycling the optical driver at a minimum duty cycle and frequency in order to maintain the switch state and the resulting antenna configuration.
  • FIG. 1A illustrates reconfigurable antenna aperture 100 of one embodiment of the present invention.
  • Aperture 100 comprises a matrix of metallic pad elements (PEs) 110 arranged in an array 116 .
  • pad elements 110 are mounted onto a printed circuit board 120 .
  • the printed circuit board 120 is suspended over a ground plane 130 to form an antenna, as illustrated in FIG. 1B .
  • Aperture 100 further comprises a plurality of switches (S) 140 which function to couple or decouple neighboring pad elements 110 together.
  • S switches
  • one of the pad elements 110 is driven by an electrical signal.
  • the pattern in which current flows from center element 115 through pad elements 110 of aperture 100 can be reconfigured, enabling the ability to reconfigure the resulting radiation pattern from aperture 100 .
  • the pattern of current flow can thusly be reconfigured to create antenna array patterns, such as but not limited to a bent wire pattern and a spiral pattern, each with known radiation patterns.
  • switches 140 are optically driven switches.
  • switches 140 comprise a switching device (Q) 220 coupled between a first pad element (PE 1 ) 210 - 1 and a second pad element (PE 2 ) 210 - 2 .
  • switching device 220 is a transistor, such as a field effect transistor (FET) having a source 241 , a drain 242 and a gate 243 .
  • FET field effect transistor
  • first pad element 210 - 1 and second pad element 210 - 2 are coupled to source 241 and drain 242 , respectively.
  • switches 140 further comprise at least one photodiode 225 coupled to gate 243 of switching device 220 .
  • photodiode 225 comprises one or more photodiodes connected in series.
  • switching device 220 couples and decouples first pad element 210 - 1 and second pad element 210 - 2 in response to a light signal 250 produced by light source 260 .
  • switching device 220 is a depletion mode device requiring the application of a negative voltage across gate 243 and source 241 to decrease current flow from source 241 to drain 242 (i.e. to open the switch).
  • switching device 220 is an enhancement mode device that is normally off when there is no voltage across gate 243 and source 241 and allows current flow upon application of a sufficient positive voltage across gate 243 and source 241 .
  • a switching voltage Vs is produced across gate 243 and source 241 sufficient to prevent current flow from first pad element 210 - 1 to second pad element 210 - 2 .
  • the minimum voltage (Vmin) sufficient to shut off switch device 220 is a function of the particular transistor used to realize switch device 220 , and can be readily ascertained by one skilled in the art upon reading this specification.
  • Vmin minimum voltage
  • a discharge resistor 226 is connected in parallel with photodiode 225 to discharge residual voltage once light signal 250 has been removed.
  • light source 260 is one of, but not limited to, a light emitting diode, a laser light, and a vertical cavity surface emitting laser (VCSEL), or similar light source adapted to generate a light beam sufficiently focused to illuminate a photodiode 225 of one switch 140 without interfering with the operation of a neighboring switch 140 on aperture 100 .
  • VCSEL vertical cavity surface emitting laser
  • Embodiments of the present invention take advantage of capacitances within switch 140 to maintain Vs above Vmin without the need to continuously maintain light signal 250 from light source 260 by duty cycling light signal 250 with a sufficient “on” duration and frequency.
  • FIG. 3 illustrates the relationship between light signal 250 and the voltage Vs over time.
  • the gate 243 to drain 242 junction of switching device 220 has a very high impedance and therefore draws little current.
  • Vs When light signal 250 is removed (shown at 310 ), Vs does not immediately collapse to zero but is supported (shown at 320 ) by the intrinsic capacitances possessed by one or both of switching device 220 and photodiode 225 . These capacitances store energy which will continue to support Vs after light signal 250 is removed.
  • the rate of collapse for Vs is a function of those capacitances and the resistance of discharge resistor 226 .
  • embodiments of the present invention cycle light signal 250 on and off.
  • Light signal 250 is cycled on for a sufficient duration (t 1 ) and with sufficient periodicity (t 1 +t 0 ) to generate a Vs greater than Vmin such that Vs does not discharge below Vmin during the part of the cycle that light signal 250 is off (t 0 ).
  • a capacitor (Cap) 227 may be optionally coupled across gate 243 and source 241 to increase the time constant that controls the decay time of Vs.
  • the electric power consumption required by light source 260 to generate light signal 250 is a function of the ratio of the duration light signal 250 is on (t 1 ) to the sum of time light signal 250 is off (t 0 ) and on (t 1 ).
  • the power consumed by light source 260 will be only 1 ⁇ 3 of that consumed when light source 260 is continuously on.
  • the ratio of t 1 to t 0 and the total cycle period t 1 +t 0 for a particular application can be readily determined based on the capacitances of photodiode 225 , switching device 220 , capacitor 227 and the resistance of resistor 226 .
  • capacitor 227 and resistor 226 one skilled in the art upon reading this specification would also appreciate the tradeoff between the decay time of Vs and the speed at which aperture 100 can be reconfigured. When fast switching is required for fast reconfiguration of aperture 100 , Vs must decay quickly. In one embodiment, when a shorter Vs decay time is required, a small capacitance value is chosen for capacitor 227 .
  • capacitor 227 is omitted. In that case, embodiments of the present invention rely on the intrinsic capacitance of one or more of photodiode 225 and switching device 220 . When fast switching is not required for reconfiguration of aperture 100 , then the decay time of Vs can be longer and a larger capacitance value chosen for capacitor 227 .
  • the capacitance of capacitor 227 and the values for t 1 and t 0 can thus be readily determined by one skilled in the art upon reading this specification.
  • an aperture 100 further comprises a plurality of light sources 460 each controlled by an associated driver 410 .
  • light sources 460 are each VCSELs such as, but not limited to the VCE-F85B20 manufactured by Lasermate Group, Inc.
  • light sources 460 are embedded into ground plane 130 and positioned to illuminate exactly one of switches 140 .
  • each driver 410 controls one or more of light sources 460 .
  • drivers 410 are drivers such as, but not limited to the STP16CL596 manufactured by STMicroelectronics.
  • an antenna configuration controller 420 is coupled to communicate the desired antenna array pattern to drivers 410 .
  • antenna configuration controller 420 is a TMS320c6711 digital microprocessor manufactured by Texas Instruments.
  • each driver will turn off one or more of switches 140 by turning on one or more of light sources 460 .
  • a duty cycle controller 430 is also coupled to drivers 410 to communicate a duty cycle signal to each of drivers 410 for cycling light sources 460 .
  • duty cycle controller 430 is coupled to an output enable pin of an STP16CL596.
  • drivers 410 will cycle the associated light sources 460 on (for time t 1 ) and off (for time t 0 ) as directed by duty cycle controller 430 .
  • duty cycle controller 430 outputs a duty cycle signal comprising a square wave signal with a signal low for time t 1 and a signal high for time t 0 .
  • FIG. 5 is a flow diagram illustrating a method for antenna reconfiguration switching of one embodiment of the present invention.
  • the method begins at 510 with directing a light signal at an optically controlled switch.
  • the optically controlled switch is switch 140 as illustrated in FIGS. 1 and 2 .
  • the optically controlled switch is adapted to control the flow of current between two pad elements based on the light signal.
  • the method then proceeds to 520 with cycling the light signal on and off.
  • the light signal must cycle on for a sufficient duration to generate a switching voltage, Vs, that is greater than a minimum voltage, Vmin, required to operate a switching device (such as switching device 220 ).
  • Vs must be more negative than Vmin to open the switching device and stop current flow between the two pad elements. When Vs is less negative than Vmin, then the switching device closes, allowing current flow between the two pad elements.
  • the light signal must be cycled on for a sufficient duration of time and with a sufficient periodicity to maintain the switching device in the open state.
  • the method when the light signal is on and received by one or more photodiodes of the optically controlled switch, the method further comprises generating a switching voltage, Vs, from the light signal and applying the switching voltage across a gate-source junction of a transistor. While the photodiode is producing the switching voltage, electrical energy from the voltage is stored by one or more intrinsic capacitances of the photodiode and switching device, and in one embodiment, by one or more capacitors. When the light signal is cycled off, the stored electrical energy maintains Vs above Vmin for a limited duration of time. The light signal is then cycled on again before Vs can decay below Vmin.
  • Vs switching voltage
  • the duration and periodicity for cycling the light signal on and off is based on a duty cycle signal which is communicated to a driver that controls the light signal.
  • the driver cycles the light signal on and off based on the duty cycle signal.
  • the antenna array pattern is also communicated to the driver that control the light signal.
  • only light signals specified by the antenna array pattern are cycled on and off based on the duty cycle. Embodiments of the present invention thus reduce the amount of power consumption required to maintain an antenna aperture in a given antenna array pattern because the duty cycling of the light signals reduces the electric power consumption required by light source that generate the light signals.
  • embodiments of the present invention illustrated in this specification demonstrate maintaining optically controlled switches in an open state by duty cycling a light source
  • embodiments of the present invention are not limited to only maintaining optically controlled switches in an open state.
  • one skilled in the art would appreciate that the scope of the present invention equally includes embodiments where light signals maintain optically controlled switches in a closed state.
  • this specification demonstrates duty cycling optical signals for optical switches in antenna application
  • the scope of embodiments of the present invention also include any optical switching system for coupling together other devices by maintaining an optically generated switching voltage at a level greater than a minimum voltage by duty cycling a light source.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)
US11/253,188 2005-10-18 2005-10-18 Low power switching for antenna reconfiguration Expired - Fee Related US7335871B2 (en)

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US11/253,188 US7335871B2 (en) 2005-10-18 2005-10-18 Low power switching for antenna reconfiguration
EP06117513A EP1777820A3 (de) 2005-10-18 2006-07-19 Leistungsarmes Schalten für Antennen-Rekonfiguration

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US11/253,188 US7335871B2 (en) 2005-10-18 2005-10-18 Low power switching for antenna reconfiguration

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8285305B2 (en) 2010-09-13 2012-10-09 Honeywell International Inc. Notifying a user of an event
US8457179B2 (en) 2010-09-13 2013-06-04 Honeywell International Inc. Devices, methods, and systems for building monitoring
US10003131B2 (en) 2013-11-19 2018-06-19 At&T Intellectual Property I, L.P. System and method of optical antenna tuning

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US20090146894A1 (en) * 2007-12-05 2009-06-11 Honeywell International Inc. Reconfigurable antenna steering patterns
US8373608B2 (en) * 2007-12-05 2013-02-12 Honeywell International Inc. Reconfigurable antenna pattern verification
DE102011087696A1 (de) * 2011-12-05 2013-06-06 Semikron Elektronik Gmbh & Co. Kg Halbleiterbaustein, Treiber und Herstellungsverfahren
DE102018007284B4 (de) * 2018-09-14 2020-04-02 Diehl Metering Gmbh Pulsgeber

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8285305B2 (en) 2010-09-13 2012-10-09 Honeywell International Inc. Notifying a user of an event
US8457179B2 (en) 2010-09-13 2013-06-04 Honeywell International Inc. Devices, methods, and systems for building monitoring
US8588820B2 (en) 2010-09-13 2013-11-19 Honeywell International Inc. Notifying a user of an event
US9008697B2 (en) 2010-09-13 2015-04-14 Honeywell International Inc. Notifying a user of an event
US10003131B2 (en) 2013-11-19 2018-06-19 At&T Intellectual Property I, L.P. System and method of optical antenna tuning
US11177574B2 (en) 2013-11-19 2021-11-16 At&T Intellectual Property I, L.P. System and method of optical antenna tuning

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US20070084987A1 (en) 2007-04-19
EP1777820A2 (de) 2007-04-25
EP1777820A3 (de) 2008-04-16

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